Dario Braga, Fabrizia Grepioni, Laura Chelazzi, Manuela Campana, Donatella Confortini and Giuseppe C. Viscomi
Received 8th June 2012, Accepted 3rd August 2012
DOI: 10.1039/c2ce25920f

The crystal structures of four crystal forms of rifaximin, named alpha, beta, delta and epsylon have been elucidated by a combination of single crystal and powder diffraction experiments with synchrotron and X-ray sources. The crystal structures of the delta and epsylon forms have been determined from powder diffraction data alone. Hot stage microscopy has also been of paramount importance in the understanding of the beta-alpha conversion process.